Yajie Zhang1,2, Jeroen B J Smeets3, Eli Brenner3, Sabine Verschueren4, Jacques Duysens5. 1. Department of Rehabilitation Sciences, FaBer, KU Leuven, Leuven, Belgium. yajie.zhang19@gmail.com. 2. Department of Human Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands. yajie.zhang19@gmail.com. 3. Department of Human Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands. 4. Department of Rehabilitation Sciences, FaBer, KU Leuven, Leuven, Belgium. 5. Motor Control Laboratory, Movement Control and Neuroplasticity Research Group, FaBer, KU Leuven, Leuven, Belgium.
Abstract
PURPOSE: Human sensory and motor systems deteriorate with age. When walking, older adults may therefore find it more difficult to adjust their steps to new visual information, especially considering that such adjustments require control of balance as well as of foot trajectory. Our study investigates the effects of ageing on lower limb responses to unpredictable target shifts. METHODS: Participants walked on a treadmill with projected stepping targets that occasionally shifted in the medial or lateral direction. The shifts occurred at a random moment during the early half of the swing phase of either leg. Kinematic, kinetic and muscle activity data were collected. RESULTS: Older adults responded later and corrected for a smaller proportion of the shift than young adults. The order in which muscle activation changed was similar in both groups, with responses of gluteus medius and semitendinosus from about 120 to 140 ms after the shift. Most muscles responded slightly later to lateral target shifts in the older adults than in the young adults, but this difference was not observed for medial target shifts. Ageing delayed the behavioural responses more than it did the electromyographic (EMG) responses. CONCLUSIONS: Our study suggests that older adults can adjust their walking to small target shifts during the swing phase, but not as well as young adults. Furthermore, muscle strength probably plays a substantial role in the changes in online adjustments during ageing.
PURPOSE:Human sensory and motor systems deteriorate with age. When walking, older adults may therefore find it more difficult to adjust their steps to new visual information, especially considering that such adjustments require control of balance as well as of foot trajectory. Our study investigates the effects of ageing on lower limb responses to unpredictable target shifts. METHODS:Participants walked on a treadmill with projected stepping targets that occasionally shifted in the medial or lateral direction. The shifts occurred at a random moment during the early half of the swing phase of either leg. Kinematic, kinetic and muscle activity data were collected. RESULTS: Older adults responded later and corrected for a smaller proportion of the shift than young adults. The order in which muscle activation changed was similar in both groups, with responses of gluteus medius and semitendinosus from about 120 to 140 ms after the shift. Most muscles responded slightly later to lateral target shifts in the older adults than in the young adults, but this difference was not observed for medial target shifts. Ageing delayed the behavioural responses more than it did the electromyographic (EMG) responses. CONCLUSIONS: Our study suggests that older adults can adjust their walking to small target shifts during the swing phase, but not as well as young adults. Furthermore, muscle strength probably plays a substantial role in the changes in online adjustments during ageing.
Entities:
Keywords:
Correction; Elderly; Force; Leg adjustments; Target jump
Authors: Judith Hegeman; Vivian Weerdesteyn; Bart van den Bemt; Bart Nienhuis; Jacques van Limbeek; Jacques Duysens Journal: Gait Posture Date: 2012-05-05 Impact factor: 2.840